Resistance Training with Instability Does Not Hamper Total Training Volume and Muscle Strength Gains in Older Adults: a Secondary Analysis from REI Study

Abstract

Background: Resistance training with instability (REI) emerged as a promising training modality for older adults aiming to counteract age-related changes.

Objectives: We compared the effects of 12 weeks of REI and traditional resistance exercise (RE) on muscle strength in older adults with cognitive impairment. We further explored if total training volume (TTV) significantly differs among training groups.

Methods: This is a secondary analysis of the REI study. Participants were randomly assigned to REI (n=22) or RE (n=23). RE protocol involved moderate-intensity, free-weight, and machines-based resistance exercises (3 sets, 10-15 repetitions). REI received a similar training protocol, in which exercises were simultaneously performed with instability/unstable devices (e.g., squat exercise under a foam pad or Bosu^® ball). Maximal isometric strength and isokinetic parameters were assessed at baseline and after completion of a 12-week intervention through a hydraulic handgrip and isokinetic dynamometer, respectively. TTV (sets × repetitions × load) was computed based on external training load over the 12 weeks.

Results: No differences were observed between groups (p=.35) after the intervention. Over 12 weeks, REI and RE improved isometric handgrip strength (p<.001) and isokinetic performance (p=.04). We also did not find differences in the TTV between training groups (p=.28).

Conclusion: We demonstrated that both REI and RE training induced similar gains in muscle strength. Combining unstable surfaces/instability devices did not hamper TTV, which may have clinical applications in the context of exercise for older adults.

Keywords: aging; instability; muscle strength; resistance training.

FIGURE 1

Squat exercise with the addition of instability

FIGURE 2

The flow diagram of secondary analysis of the REI Study

FIGURE 3

Regression line indicating the TTV slope (sets × repetitions × load) between the training groups in the trunk and upper limbs exercises (panel A) and lower limbs (panel B) over the 12 weeks of training Blue and yellow dots represent RE and REI groups, respectively. Dashed lines show 95% confidence intervals (95%CI). TTV is expressed in arbitrary units.